(1) Field of the Invention:
This invention relates to an improved process for producing o-alkylated phenols from anisoles.
(2) Description of the Prior Art:
A number of studies have been made on the process for the production of o-alkylated phenols, particularly 2,6-dimethyl phenol, which is used as the starting material for the production of polyphenylene oxides as useful plastics.
A number of processes for synthesizing o-alkylated phenols by the gaseous phase catalytic reaction of a phenol and an alcohol as the starting material on various kinds of metallic oxides have been known, and there are processes for the synthesis thereof on an industrial scale including a process in which aluminium oxide is used, a process in which magnesium oxide is used as the metallic oxide catalyst respectively, and the like.
Studies have been made on the reaction mechanism for the synthesis of 2,6-xylenol from phenol and methanol by the use of magnesium oxide as the catalyst with the result that (i) no anisole can be formed as an intermediate reaction product, that is, neither o-cresol nor 2,6-xylenol are formed therefrom via an anisole as an intermediate, that (ii) when anisole is solely used as the starting material, a thermal decomposition takes place in the neighborhood of 500.degree. C. to form mainly phenol and benzene, and that (iii) even when anisole and methanol are used as the starting material for reaction, the reaction proceeds to a low extent at 500.degree. C. or lower.
During the production of o-alkylated phenols from phenols and alcohols as the starting material, various kinds of compounds are formed as by-products, and these by-products should be effectively utilized. It is an important problem to be solved to effectively convert anisoles as one of the by-products to o-alkylated phenols to be utilized.